Method of bonding using urethane base pressure sensitive adhesives

ABSTRACT

A pressure sensitive adhesive product is produced by casting on a substrate web, such as paper, plastic film, or metal foil, a layer of an admixture consisting essentially of; A. a diene polymer or copolymer having at least 1.6 terminal active-hydrogen groups and an equivalent weight of 500 or more, B. an organic polyisocyanate and C. at least 75 parts per 100 parts of the diene polymer and the organic polyisocyanate of a tackifying resin or mixture of tackifying resins having a ball and ring softening point of 60* to 140*C that has been predissolved in the diene polymer, and coreacting the diene polymer and the organic polyisocyanate in situ on the substrate web to give a pressure sensitive adhesive product. The diene polymer and the organic polyisocyanate, plus any other ingredients coreactive with the diene polymer and the organic polyisocyanate that are used, are chosen so that the pressure sensitive adhesive polymer formed on the substrate web has the character of an elastomer.

United States Patent [1 1 Kest 1 1 Apr. 22, 1975 METHOD OF BONDING USINGURETHANE BASE PRESSURE SENSITIVE ADI-IESIVES [21] Appl. No.: 357,083

Related US. Application Data Division of Ser. No. 144.337. May 17, 1971,Pat. No.

3,743,617, which is a continuation-in-part of Ser. No. 843,750, July 22,1969. abandoned.

[52] US. Cl. 156/289; 117/122 PA; 117/161 A; 117/161 UD; 117/161 UN;156/331;

161/255; 260/27 BB; 260/859 R; 260/876 B [51] Int. Cl. C09j 5/00; B32b31/12 [58] Field of Search ..117/122 P, 122 PA, 161 A, 117/161 UD, 161UN; 156/278, 331, 289;

161/255; 260/27 R, 27 BB, 859 R, 876 B [56] References Cited UNlTEDSTATES PATENTS 2,964,422 12/1960 Bergstedt ct a1 1 17/76 3,246,0494/1966 Webber 260/829 3,437,622 4/1969 Dahl 260/24 3,515,773 6/1970 Dahl117/122 P 3,532,652 10/1970 Zang et a1 1 260/859 3,584,075 6/1971 Bocket a1.... 260/24 3,607,976 9/1971 Hsich 260/859 3,617,361 11/1971Reinhard et a1. 260/859 3,625,752 12/1971 Korpman 117/122 P FOREIGNPATENTS 0R APPLICATIONS 772,222 11/1967 Canada 260/77.5

OTHER PUBLICATIONS Poly B-D" Product Data Bulletin No. 505; SinclairPetrochemicals, Inc., New York, May 1, 1965. pp. 1-7, 9, 12, 13, 21-24and 41-46.

Primary E.\'aminer-Douglas .1. Drummond Assistant Examiner-Robert A.Dawson Attorney, Agent, or FirmTeare, Teare & Sammon [57] ABSTRACT Apressure sensitive adhesive product is produced by casting on asubstrate web, such as paper, plastic film, or metal foil, a layer of anadmixture consisting essentially of;

A. a diene polymer or copolymer having at least 1.6 terminalactive-hydrogen groups and an equivalent weight of 500 or more,

B. an organic polyisocyanate and C. at least parts per parts of thediene polymer and the organic polyisocyanate of a tackifying resin ormixture of tackifying resins having a ball and ring softening point of60 to C that has been predissolved in the diene polymer, and coreactingthe diene polymer and the organic polyisocyanate in situ on thesubstrate web to give a pressure sensitive adhesive product. The dienepolymer and the organic polyisocyanate, plus any other ingredientscoreactive with the diene polymer and the organic polyisocyanate thatare used, are chosen so that the pressure sensitive adhesive polymerformed on the substrate web has the character of an elastomer.

16 Claims, No Drawings METHOD OF BONDING USING URETHANE BASE PRESSURESENSITIVE ADHESIVES CROSS REFERENCES TO RELATED APPLICATIONS Thisapplication is a division of application Ser. No. 144,337 filed May 17,1971, now US. Pat. No. 3,743,617. Application Ser. No. 144,337 is acontinuation-in-part of US. Ser. No. 843,750 filed July 22. 1969, nowabandoned, and is directed to a specific class of pressure sensitiveadhesives falling within the generic class of pressure sensitiveadhesives described and claimed in US. Ser. No. 843,793 also filed July22, 1969, now abandoned, and its successor continuationin-partapplication Ser. No. 144,293 filed May 17, 1971 and now U.S. Pat. No.3,743,616.

BACKGROUND OF THE lNVENTION This invention relates generally to a newclass of and method for producing pressure sensitive adhesives. Moreparticularly, this invention encompasses a method of producing a newclass of pressure sensitive adhesive products by the in situ formationdirectly on the product of a solid, elastomeric polymer derived from thereaction of a low-molecular weight, diene polymer having reactivefunctional groups and a polyfunctional organic compound havingfunctional groups coreactive with the polymer functional groups in thepresence of particular types and quantities of tackifying resins, whichproducts have a spectrum of properties unattainable with pressuresensitive adhesives presently known and available to the art.

Pressure sensitive adhesive products encompass typically webs of paper,plastic film or sheets, or metal foils carrying one one side a coatingor layer of a solventless, solid adhesive composition that possessessufficient tackiness or tack, as it is referred to in the art, to permitsuch webs of paper, plastic or metal to be adhered to the surface of anobject by merely contacting and momentarily pressing the adhesivelayer-carrying side of the web directly against the object surface.

ln formulating pressure sensitive adhesive compositions, the skilledadhesive artisan is concerned with producing a composition that willhave a certain minimum balance of physical and chemical properties so asto be able to withstand the stresses and environment that the productwill encounter and be expected to survive in use.

Generally, in the technology of pressure sensitive adhesives, thephysical properties known in the art as tack, peel adhesion, and creepresistance are paramount in determining the suitability of any givenpressure sensitive adhesive composition to provide the necessaryapplication properties and in-service durability required of thepressure sensitive adhesive product.

The first property, tack, is in effect the instantaneous adhesion of theadhesive layer of the web to the surface of an object that is developedimmediately after contacting the web with the surface. One widelyaccepted method of measuring tack, endorsed by the Pressure SensitiveTape Council, is test method PSTC-6 evolved and published as a standardtest by the council. It involves rolling a stainless steel ball down aninclined plane unto the surface of a pressure sensitive adhesive layerdeposited on a horizontal plane, and measuring the distance in inches,the ball rolls across the adhesive. In this test, tack is expressed ininches of ball travel,

and this is an inverse function of the distance the ball rolls high tackadhesive stopping the ball within 0.5 to 3 inches, low tack adhesivesallowing the ball to roll more than 12 inches.

The second important property, peel adhesion, is the adhesion of thepressure sensitive adhesive product after the adhesive layer has been incontact with an adherent surface 2 for a sufficient period of time toreach a steady state or equilibrium with the surface. It is normallymeasured by American Standards Test Method (ASTM) D-903-49, whichinvolves pressing a 1 inch wide strip of an adhesive-coated web unto atest surface, such as a metal or glass plate. allowing the laminate toage under specified conditions of time, temperature and humidity, andthen peeling the web from the plate at a 180 angle at a peeling rate of6 inch/minute. For pressure sensitive adhesive products that are meantto be only temporarily adhered, such as masking tapes and descriptivelabels, peel adhesion of 2 pounds or less is usual. Conversely, productsthat are to be permanently adhered, such as product, trademark orinstruction labels, must exhibit peel adhesion of at least 3 pounds withlevels of 5 pounds or more being preferred.

The third physical property utilized to define the suitability of apressure sensitive adhesive product for a given use is its creepresistance. This test measures in essence the durability and permanenceof the adhesive bond of the adhered product when subjected to a constantdelaminating force, such as would be present when a pressure sensitiveadhesive product is adhered to a vertical or convex surface. It ismeasured by the Pressure Sensitive Tape Councils test method PSTC-7 thatconsists of overlapping 1 inch of a 1 inch wide web unto a test surface,such as a plate of metal or glass, conditioning the test specimen for aspecified period under standard temperature and humidity conditions, andthen imposing a 2 pound continuous separation force on the specimen in adirection coaxial to the length of the web in a 0.5F air environment,and measuring the time for the web to pull away from the plate. Ideally,pressure sensitive adhesive products, whether removable or permanent,are sought that exhibit no separation. In reality, however, productswithstanding 50 hours or more of stress are considered to be superiorand with the normal range being 20 to 40 hours.

Besides these physical property parameters, the chemical attributes ofthe pressure sensitive adhesive composition must also be considered inorder to provide a pressure sensitive adhesive product having therequisite durability in the environment in which it is to be used. Thus,for example, the pressure sensitive adhesive must be formulated so as toexhibit resistance to adhesive-degrading environmental conditions suchas elevated temperatures, sunlight, organic solvents, moisture, acids,and bases to which the pressure sensitive adhesive product will beexposed in service.

PRIOR ART PROCESSES FOR MANUFACTURING PRESSURE SENSITIVE ADHESIVEPRODUCTS In the art of pressure sensitive adhesives, several processeshave been developed for the purpose of producing such pressure sensitiveadhesives on a commercially satisfactory basis. One method involves theuse of adhesive components that are dissolved in a solvent resulting ina liquid solution. A second method uses adhesive components that arefinely divided and suspended in water forming an aqueous dispersioncommonly called a latex composition. The solution or latex adhesivecomposition is applied to a substrate web such as paper, plastic film ormetal foil after which heat is applied to remove the solvents or water,leaving only the solid portion of the adhesive on the substrate.

Generally speaking, the former is known as the solvent process ofmanufacturing pressure sensitive adhesives and the latter is known asthe latex process of manufacturing pressure sensitive adhesives.Numerous formulations exist in the prior art for producing pressuresensitive adhesives by these two methods.

The disadvantages of the solvent system and the latex system ofproducing pressure sensitive adhesives are numerous:

A first disadvantage is the relatively high cost of equipment due to thefact that long and expensive heating ovens are required to evaporatesolvent or water in the solvent or latex processes, respectively. Inaddition, such ovens require sophisticated and expensive web handlingequipment and controls. Because of the length of these ovens, scraplosses of the substrate web being coated with the pressure sensitiveadhesive are high, typically 8 to 10%, because of the excessive materialneeded to initially thread the coating machine and oven and subsequentlyconsumed in establishing the desired coating conditions and adhesivecoating weight.

A second disadvantage is the relatively slow speeds at which substratewebs can be coated with solution or latex pressure sensitive adhesivesdue to the limited speeds at which ovens can remove solvent or waterfrom the adhesive mass, especially if the adhesive layer is thick, e.g.,greater than 3 mils.

A third very serious problem is that of air pollution and the cost ofits control caused by the volatilization of solvents during themanufacture of solvent-based pressure sensitive adhesives.

A fourth problem is the ever present fire and explosion hazards wheneverflammable solvents are used and with some solvents the danger to thehealth of the workers.

A fifth problem with regard to the fact that during the application ofthe considerable heat required to remove solvents or water, the carrierweb can be damaged. For example, a paper web can be demoisturizedcausing shrinking while a plastic web can be distorted, causing severeproblems both from a production standpoint and in the quality of thefinished product.

PRIOR ART PRESSURE SENSITIVE ADHESIVE COMPOSITIONS The oldest and stillwidely used pressure sensitive adhesive compositions were based onnatural rubber as the film former often further compounded withnaturally occuring resinous products such as resin and coal tar pitch toenhance tack and peel adhesion and plasticizing petroleum oils toincrease flow properties of the adhesive. Later, when syntheticbutadiene and butadiene-styrene rubbers were developed, they were usedto replace all or part of the natural rubber in pressure sensitiveadhesive compositions.

Pressure sensitive adhesives based on these 100% hydrocarbon polymers(i.e., natural or synthetic butadiene type) and usually referred to asconventional pressure sensitive adhesives, presently constitute thelargest share of the total pressure sensitive adhesive market because oftheir low cost and their overall balance of desirable properties. Forexample, these conventional pressure sensitive adhesives can becompounded to give an acceptable level of adhesion to a wide variety ofsurfaces, both of a nonpolar nature such as polyethylene, polypropyleneand dirty surfaces (i.e., having a layer of contaminating oil) and of apolar nature such as metal, glass, polyvinyl chloride and so forth.Typical of the range of properties that can be obtained are: tack 0.5 to3 inches, peel adhesion three-fourths to 4 pounds and creep resistanceof 20 to 40 hours depending on the tack and peel adhesion values.

However, such conventional pressure sensitive adhesives are notuniversally acceptable because of poor chemical resistance inenvironments such as oils, hydrocarbon solvents, oxidizing acids, hightemperatures and sunlight that cause the pressure sensitive adhesiveproducts to fail prematurely or to be deficient in adhesive bondstrength.

In an effort to overcome their environmental deficiencies, the adhesivetechnologist has produced pressure sensitive adhesives from more polarrubbers such as polychloroprene or butadiene acrylonitrile copolymersthat inherently have greater chemical resistance to such hydrocarbonrubber degrading environments. While such polar rubbers provide pressuresensitive adhesives with better ability to withstand such environmentsas exposure to hydrocarbon solvents, elevated temperatures and oxidizingacids and to some extent, sunlight, these improvements were not obtainedwithout sacrifice of the equally important properties of tack and peeladhesion. Generally, it is observed in the tack testing of these polarpressure sensitive adhesives that the ball travel in the PSTC-6 test is12 inches or more, a figure four times poorer than the poorest tack ofconventional hydrocarbon polymer-based pressure sensitive adhesives.Further, even poorer tack is observed at low temperatures such as 50F orless. At the same time, while respectable peel adhesion, e.g. 4 to 6pounds, and creep resistance, e.g. 30 to hours, can be obtained, suchadhesion values are only observed when the polar-type pressure sensitiveadhesives are applied to polar surfaces such as metal or glass, it beingimpossible within the knowledge of the present state of the art toformulate them, so as to be adhesive to nonpolar surfaces such aspolypropylene, even though there is a present need for their improvedenvironmental resistance properties in applications involving nonpolaradherent substrates.

A further serious drawback of the polar-type pressure sensitive adhesiveis economic. The polar polymer employed requires more expensivetackifying resins and considerably more expensive solvents such asmethyl ethyl ketone and tetrahydrofuran.

In an effort to obtain better peel adhesion and creep resistanceproperties and even greater resistance to heat and especially sunlightexposure, there has been developed within the last fifteen years,pressure sensitive adhesive formulations based on vinyl polymers havinginherent UV and heat resistance, principally polymers based on theacrylate monomers such as methyl methacrylate, ethyl acrylate and soforth. Here again, however, the adhesive technologist was thwarted inhis attempt to provide a universally excellent pressure sensitiveadhesive. While excellent sunlight and heat resistance were obtained,tack was even poorer, than the polar pressure sensitive adhesiveexhibiting 15 inches or more of ball roll in the PSTC-6 test. Inaddition, tack was similarly temperature dependent, being almostnon-existent at temperatures below 40F. Further, while improved peeladhesion, e.g. 5 to 8 pounds, and creep resistance, e.g. no failureafter seven days of testing, could be obtained, pressure sensitiveadhesives based on acrylate ester polymers, like the polar pressuresensitive adhesive, only show these improved adhesion characteristics topolar surfaces, again leaving a large spectrum of potential applicationsinvolving nonpolar substrates to be served only with conventionalhydrocarbon-based pressure sensitive adhesives having the poorenvironmental resistance characteristics hereinbefore described.

Another type of polar-type pressure sensitive adhesives that evolvedwere based on polyurethane derived from the condensation of a polyetheror polyester polyol with a polyisocyanate in the presence of a limitedamount of a tackifying resin and plasticizer. For example, U.S. pat. No.3,437,622 (Dahl) exemplifies and claims the reaction of polypropyleneether glycols having molecular weights of 400 to 3,000 and/orpolypropylene ether triols having molecular weights of 3,000 to 10,000with organic diisocyanates in the presence of 2 to 10% by weight of thepolyol of selected tackifying resins and 5 to 25% of a compatibleplasticicer.

A subsequent patent of Dahl, U.S. Pat. No. 3,515,773, claims thatinternal strength and tackiness can be produced by replacing thetackifying resins with liquid, hydroxyl-terminated butadiene polymers orcopolymers (25% styrene or acrylonitrile). The examples of U.S. Pat. No.3,437,622 while alleging the formulation of tacky adhesives, do not giveany indication of the numerical values of tack or peel adhesion that canbe obtained. However, based on the teachings of column 4, lines 4 to 7and 37 to 40 relating to the lack of internal cohesive strength andnontackiness to itself, and Applicants past experience with similarpolyurethane pressure sensitive adhesives, it is believed that theadhesive taught in U.S. Pat. No. 3,437,622 cannot be formulated to givea desired balance of tack, peel adhesion, creep resistance, andenvironmental resistance, and further that excellence in one or two ofthese properties can only be obtained at a commercially unacceptablesacrifice of the other properties. U.S. Pat. No. 3,515,733 is similarlyvague with regard to the actual physical parameters of the pressuresensitive adhesives that are illustrated in Examples 1 to 3. In general,however, based on its high content of the same polyurethane polymers,viz. 90% to 97%, exemplified in U.S. Pat. No. 3,437,622 it is believedthat the pressure sensitive adhesives therein disclosed would have thesame infirmities and particularly the inability to provide pressuresensitive adhesives having a balance of the critical properties of hightack and peel adhesion and good creep resistance and environmentalresistance. Further, because of the polar nature of the polyetherurethane employed, the pressure sensitive adhesives disclosd in bothU.S. Pat. No. 3,437,622 and 3,515,733 would be expected to exhibit pooradhesion to non-polar substrates and hence be excluded from suchapplications,

U.S. Pat. Nos. 3,246,049 discloses that pressure sensitive adhesives canbe made from polyurethanes derived from the interaction of a castoroil/diglycolic acid polyester and a polyisocyanate used either bythemselves or in combination with tackifying resins. Example Billustrates the use of 45 parts of a phenolated terpene resin, whileExample G shows the incorporation of 33 parts of an alpha pinene polymerper parts of the polyurethane. The disclosure of Column 1, lines 50 to53 and the quick stick values of the pressure sensitive adhesives ofExamples F to K shown in Column 3, lines 70 to 73, again demonstratethat presently known polyurethane pressure sensitive adhesives do notprovide excellence in certain properties without sacrificing otherequally important physical properties such as peel adhesion. Similarly,because of the polar nature of the urethane polymers used in U.S. Pat.No. 3,246,049, it would not, it is believed, give pressure sensitiveadhesives exhibiting that degree of adhesion to nonpolar surfaces thatwould be required for commercial acceptance.

Beyond the above enumerated inherent limitations of the different typesof pressure sensitive adhesives presently known in the art, the adhesivetechnologist is confronted with the problem of continually upgrading theproperties, both physical and chemical, of pressure sensitive adhesivesso as to allow pressure sensitive adhesive products to be used in newapplications having ever more stringent and demanding requirements. Inhis effort to do so, however, he is confronted with a phenomonen,previously alluded to, that is often observed in the technology offormulating compositions that are to meet a spectrum of specifiedphysical and chemical properties, namely, that to obtain excellence inone or more properties, other equally critical properties must becompromised. Thus, at the present state of the art, the adhesivetechnologist in formulating pressure sensitive adhesives exhibitingoutstanding creep resistance especially at higher temperatures, e.g. Fand more, usually does so at the expense of decreased tack and possiblypeel adhesion depending on the type of adhesive. Similarly, improvedtack presently can only be obtained usually by sacrificing the creepresistance and possibly the peel adhesion of the pressure sensitiveadhesive product. Finally, when higher peel adhesion is the goal, thenlower creep resistance and sometimes tack usually results.

A similar tradeoff in the form of decreased physical properties is oftenobserved when pressure sensitive adhesives are formulated to enhancechemical properties to improve environmental resistance characteristicsof pressure sensitive adhesive products.

As a consequence of these inherent limitations of the current pressuresensitive adhesive technology, pressure sensitive adhesive products inmany instances represent a compromise of physical and chemicalproperties just able to meet the specification requirements of the enduse, while in other instances failing to have all the necessaryproperties but still being used because nothing better is available.

For example, presently available, removable, pressure sensitive adhesivelabels have only 5 to 10 minutes creep resistance, thus giving rise towhat is known as label flagging when the edges delaminate from anadhered surface. To date, efforts to provide a pressure sensitiveadhesive having an ideal of 10 hours or more creep resistance, have beenfrustrated because peel adhesion is also raised beyond the one poundmaximum that will allow the label to be cleanly stripped off withoutinternal failure of the label stock which typically has a cohesivestrength of only about 0.75 pounds. Another example of an unsatisfactorypressure sensitive adhesive compromise resides in the production ofremovable pressure sensitive adhesive products that are based onconventional rubber-resin compositions and are applied to plastic filmsor metal foils where it is generally necessary to employ a primercoating to ensure that the adhesive layer will not transfer to theadhered surface when the product is removed. Attempts to reformulate thepressure sensitive adhesive to eliminate the need for a primer result inproducts that are deficient in either peel adhesion (too high), creepresistance or tack.

Still another example of pressure sensitive adhesive products that areless than satisfactory are permanenttype, pressure sensitive adhesiveproducts meant to be adhered to nonpolar surfaces such as polypropyleneor any type of surface contaminated with oil. Utilizing currentlyavailable materials, it is not possible to produce pressure sensitiveadhesive products having high adhesive permanence with retention ofacceptable environmental stability.

SUMMARY OF THE INVENTION Bearing in mind this present state of thetechnology of pressure sensitive adhesives hereinbefore described, it isa principal object of this invention to provide a new class of pressuresensitive adhesives that minimizes or in some instances eliminates thelimitations and deficiencies of presently used pressure sensitiveadhesive compositions and a method for their production that obviates inpart or sometimes completely, the disadvantages of manufacturingprocesses currently used to produce solvent or latex pressure sensitiveadhesive products.

More specifically, it is an object of this invention to provide a methodof producing pressure sensitive adhesive products that eliminates orgreatly reduces the need for solvents and their attendant disadvantagesincluding pollution of our environment, combustibility, toxicity andincreased costs.

A further object of the invention is the provision of a process that,even when some solvents are employed, requires simpler and lessexpensive heating means, e.g. ovens, to achieve production speeds equalto the 50 to 150 feet/minute normal today for solvent-produced pressuresensitive adhesives, or conversely, if conventional heating means areused, permits the production of pressure sensitive adhesive products atfaster speeds, e.g. 2 to 3 times more rapidly.

Another object is to provide a process of manufacturing pressuresensitive adhesive products that reduces the amount of scrap that isgenerated.

A still further particular object is the provision of pressure sensitiveadhesive compositions, having wide latitude in their ability to providean overall balance of physical and chemical properties characteristic ofthose obtained with both nonpolar and polar-type pressure sensitiveadhesives.

Yet another specific object is the provision of a pressure sensitiveadhesive composition and process that eliminates the need for a primeror removable pressure sensitive adhesive products to prevent thetransfer of the adhesive to the adhered surface when the product isremoved therefrom.

A further object is to provide adhesive compositions for removablepressure sensitive adhesives that have a low order of peel adhesion andyet high resistance to creep and which permit the production ofremovable pressure sensitive adhesive webs that adhere firmly to anobject without edge separation but can be stripped off without cohesivefailure of the web.

A still further object is to provide a pressure sensitive adhesivesystem having good adhesion to polar surfaces such as metal and glassthat maintains its tack at low temperatures, e.g. less than 40F.

Yet another objective is the provision of a pressure sensitive adhesivethat resists plasticizer migration when in contact with a plasticizedpolyvinyl chloride web or adhered surface.

In the following description and claims, the quantities of theingredients are expressed in parts by weight unless otherwise indicated.

These and other objects and advantages of my invention, which will beapparent to those skilled in the art from the following description, areobtained by my invention which comprises in its simplest basicembodiment forming in-situ on a pressure sensitive adhesive productsubstrate a layer of a pressure sensitive adhesive product substrate alayer of a pressure sensitive adhesive composition derived principallyfrom the coreaction of a liquid, low-molecular weight,hydrocarbon-backbone polymer having an average of at least about 1.6terminal, isocyanatereactive, groups per molecule and an organicpolyisocyanate to produce an elastomeric in-situ formed polymer, in thepresence of at least parts, per parts of the in-situ formed polymer, ofa tackifying resin that has a softening point between about 60C and Cand is soluble in the liquid polymer at 25C, and that further ispredissolved in the liquid polymer prior to its reaction with thepolyisocyanate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In particular the low-molecularweight, hydrocarbonbackbone polymer hereinafter referred to as the dienetelechelic polymer, that is utilized in the practice of this inventionis a liquid or quasi-liquid polymer derived from the polymerization ofbutadiene, isoprene, piperylene, chloroprene or mixtures thereof, orcopolymers derived from the random copolymerization of butadiene,isoprene, piperylene, chloroprene or mixtures thereof with up to 33% byweight of a copolymerizable vinyl monomer free of active hydrogen groupscapable of reacting with an isocyanate, which polymer has a terminalhydroxyl, mercapto, amino, or carboxyl groups (hereinafter called activehydrogen groups) attached to one of the last three carbon atoms at theend of the polymer chains, and an average of at least about 1.6 of suchactive hydrogen groups per polymer molecule. Depending on its method ofsynthesis, it is possible to obtain and use a diene telechelic polymerhaving a branched structure and thus more than two chains having suchterminally located active hydrogen groups. While diene telechelicpolymers having as many as four active hydrogen groups can be used, itis preferred to use polymers having no more than three per polymermolecule to give the viscoelastic flow properties required in theinvention pressure sensitive adhesives.

Further, to provide pressure sensitive adhesives having the necessaryelasticity and compatibility with tackifying resins, the polymer shouldhave an average equivalent weight (molecular weight of the polymerdivided by the number of active hydrogen groups in the polymer) of atleast about 500. For maximum compatibility and physical properties,polymers having an average equivalent weight of about 800 or more arepreferred. The maximum equivalent weight of polymers that are capable ofproducing acceptable pressure sen sitive adhesives, as a rule, will notexceed 3,000 and usually 2,000 to 2,500 is the normal upper limit.Bearing in mind the parameters of functionality and suitable equivalentweight, it can be seen that the molecular weight of the diene telomercan vary from as low as about 800 up to a useful maximum of about12,000.

Generally, when maximum resistance to a solvent environment is desired,diene telechelic polymers having up to about by weight of randomlycopolymerized polarmonomers such as acrylonitrile; methacrylonitrile ormethacrylamide will be used. Pressure sensitive ad hesives havingimproved sunlight resistance and heat resistance are obtained by usingdiene telomers containing up to about 33% by weight of randomlycopolymerized acrylate esters such as methylmethacrylate and ethylacrylate. Lower cost and/or modification of pressure sensitive adhesiveproperties can be obtained by using diene telechelic polymers contaningup to about 33% by weight of randomly copolymerized vinyl aromaticmonomers such as styrene, and methyl styrene and vinyl pyridine. As ageneral rule, however, maximum latitude with regard to formulating withdifferent types of tackifying resins to produce a broad spectrum ofpressure sensitive adhesives, as described hereinafter, is obtained whenthe diene telechleic polymer is derived from monomers consistingessentially of butadiene, isoprene, piperylene or mixtures thereof andhence, for most embodiments of the invention, constitute the preferredmaterial. Similarly, while satisfactory pressure sensitive adhesives canbe made with diene telomers having mercaptan amino and carboxyl endgroups, more flexibility in formulating pressure sensitive adhesiveshaving the desired processing characteristics and physical propertiescan be obtained with diene telomers having hydroxyl end groups andconsequently are preferred in the practice of this invention.

Diene telechelic polymers of the above description and methods for theirsynthesis are well known, being shown for example in US. Pat. Nos.2,877,212; 3,134,745; 3,135,716; 3,190,848; 3,285,949; 3,308,170 and3,410,836.

As some of these references show, diene telechelic polymers useful inthis invention may contain, in addition to monomer and initiator,divalent radicals of lowmolecular-weight coupling compounds which, insome instances, introduce into the diene telechelic polymer chain,groups containing 0, S or N atoms such as carbonyl, ether, ester oramide groups. Where they are present, the minimum molecular weight ofthe diene polymer segment or diene-vinyl copolymer segment between thecoupling compound radical preferably is about 500 or more to insureproper adhesive viscoelastic properties and resin compatibility in thepressure sensitive adhesives of this invention. The above describeddiene telechelic polymers can be used either singly or two or more canbe used together, if desired,

to give pressure sensitive adhesives having special properties.

in the pressure sensitive adhesives of this invention, up to about 35percent by weight of the diene telechelic polymer can be replaced by areactive polyether and/or a polyester, miscible with the dienetelechelic polymer, having about 1.6 to 4 hydroxyl, carboxyl amino ormercaptan groups, a melting point below 60C and preferably below 50C,and an equivalent weight of from about 400 up to about 1,500, which,when admixed with the diene telechelic polymer and coreacted with thepolyisocyanate employed in the invention pressure sensitive adhesive,produces a rubber-like copolymer. Because of their latitude informulating the invention pressure sensitive adhesives and furtherconsidering their ease of synthesis and commercial availability,polyether or polyesters having predominantly or only hydroxyl groups arepreferred. Exemplary of suitable polyethers are polyethylenepropyleneether polyols, polypropylene ether polyols, and polytetramethylene etherpolyols such as are shown in US. Pat. No. 2,929,800. Typical ofpolyesters that may be used are those derived from the condensation ofpolyols such as ethylene glycol, 1,4-butandiol, ispropylene glycol andglycerine with polycarboxylic acids such as succinic acid, adipic acid,sebacic acid and phthalic acid or those derived from the polymerizationof caprolactone. Generally, maximum compatibility with tackifying resinsand nonsensitivity to water in the invention pressure sensitiveadhesives is obtained by the use of polyethers or polyesters having anaverage of about three or more carbon atoms per oxygen atom in thepolymer chain and consequently are preferred. Either a single reactivepolyether or polyester or mixtures thereof can be used in the inventionpressure sensitive adhesives.

Besides the diene telechelic polymer and the reactive polyether orpolyester, there can be employed in the pressure sensitive adhesives ofthis invention, lowermolecular-weight, reactive, chain-extending orcrosslinking compounds having a molecular weight usually of about 300 orless and two to four functional groups reactive with an isocyanate suchas hydroxyl, carboxyl, amino, or mercaptan groups with hydroxyl groupsbeing preferred for maximum latitude in formulating the inventionpressure sensitive adhesives. Typical of such extending or crosslinkingcompounds that may be used either alone or in combination are ethyleneglycol, 1,4-butanediol, 1,4-cyclohexane glycol, trimethylol propane,pentaerythritol, N,N-bis 2-hydroxypropyl aniline, adipic acid, succinicacid, terephthalic acid, ethanol amine, piperazine, hydrazine, propylenediamine, 4,4'-methylene bis (2-chloroaniline), 3,3'-dichloro benzidine,4,4'-diamino-diphenyl methane and 2,4- and 2,6-toluene diamines. Whendesired, water can be used with an excess of the polyisocyanate togenerate a polyamine in situ. The quantity of extenders or crosslinkingcompounds that may be used cannot be rigidly delineated because itdepends not only on the structure, molecular weight and functionality ofthe extender or crosslinker but also on factors such as the equivalentweight and composition of the diene telechelic polymer and the reactivepolyether and polyester, if used, as well as the type and quantity ofpolyisocyanate that is employed in producing the invention pressuresensitive adhesives. All of these factors are interdependent indetermining whether the polymer produced will have the necessaryviscoelastic properties required of the pressure sensitive adhesives ofthis invention as more fully described hereinafter. Bearing in mind,these observations, it has been found that up to about 2.0 equivalentweights of some extender compound may be used per equivalent weight ofthe diene telechelic polymer or of the combined diene telechelic polymerand polyether and/or polyester. When it is desired to use crosslinkingcompounds having more than two active hydrogen groups, then generallynot more than about 1.5 equivalents per equivalent of the dienetelechelic polymer will be used if a satisfactory pressure sensitiveadhesive is to be obtained and generally, about 0.8 equivalent or lesswill be utilized. Such extending or crosslinking compounds areespecially useful in the invention pressure sensitive adhesivecomposition when the ratio of isocyanate to active hydrogen is belowabout 0.90, when the functionality of the diene telechelic polymerand/or the reactive polyether or polyester is less than about 1.8 orwhen the equivalent weight of the diene telechelic polymer and/or thereactive polyether or reactive polyester is about 1,500 or more. Inthese instances, their use provides means for insuring that thein-situ-formed pressure sensitive adhesive polymer has the desiredelastomer-like properties.

Organic polyisocyanates that may be used in forming the pressuresensitive adhesives of this invention include aromatic, aliphatic andcycloaliphatic isocyanates, as for example 2,4 toluene diisocyanate,2,6- toluene diisocyanate, p-phenylene diisocyanate, 4',4' disocyanate,diisocyante, p,p' methylene diphenyl diisocyanate, polymethylenepolyphenylisocyanate, triphenylmethane tri-isocyanate, hexamethylenediisocyanate and methylene dicyclohexyl-4,4'-diisocyanate. These andother polyisocyanates may be used either singly or in combination. Toprepare pressure sensitive adhesives having the proper viscoelasticcharacter, a major portion of the total isocyanate requirement usuallywill be provided by organic diisocyanates. In the practice of theinvention, sufficient polyisocyanate is used to provide a ratio ofisocyanate groups to the total of the active hydrogen groups present inthe diene telechelic polymer, and when used, the reactive polyester orpolyether and extending or crosslinking compound of from about 0.75 to1.20. Normally, ratios between about 0.95 and 1.12 are preferred formost pressure sensitive adhesive applications to provide an optimumbalance of properties. A ratio of less than about 0.75 produces pressuresensitive adhesives that have poorer cohesive strength, poorer creepresistance, increased tendency to transfer from the substrate web to theadhered surface, and finally increased sensitivity to environmentaldegradation. Conversely, when the ratio exceeds more than about 1.20,the invention pressure sensitive adhesives have been observed to exhibitpoor tack and peel adhesion at low temperatures (e.g. 40 F or less) andto be incapable of giving good adhesion to rough surfaces due, it isbelieved, to reduced viscoelastic flow properties. In formulating theinvention pressure sensitive adhesives, water, if used, is considered torequire one equivalent weight of the organic polyisocyanate per mole ofwater that it is desired to use in the formation of the in-situ pressuresensitive adhesive elastomer, which as previously discussed, will notgenerally be more than about 2.0 moles of water per equivalent of thediene telechelic polymer.

In some instances, it is advantageous to include in the pressuresensitive adhesive formulations of this invention, a minor quantity of amonofunctional organic regulating compound having either a singleisocyanate group or a single active hydrogen group to regulate thedegree of branching and/or crosslinking of the pressure sensitiveadhesive polymer and hence its viscoelastic properties when the averagefunctionality of all the active-hydrogen containing reactants and thepolyisocyanates being used greatly exceeds an average value of about2.4. Depending upon this value, from about 1% to about 10% equivalentsof the monofunctional regulating compound may, for example, be neededper equivalent of either the active hydrogen-containing reagent ororganic polyisocyanate present.

It has been observed that the pressure sensitive adhesives of thisinvention having the desired balance of physical and chemical propertiesare obtained when the aforedescribed diene telechelic polymer, organicpolyisocyanate and when used reactive polyether, polyester extender,crosslinker, and monofunctional regulating compound are selected withreference to their composition and quantities so as to provide, whenreacted together, an in-situ-formed polymer having elastomeric-likeproperties. Thin films (12 20 mils) of the polymer cast from a totalsolids solution, which had been vacuum deaereated, that were dried andcured 10 minutes at 175F and four days at room temperature give anelongation at break in excess of employing a standard ASTM one-fourthinch wide test dumbbell specimen at a test speed of 12 inches perminute. When a 1 X 6 inch test specimen of film of the polymer havingabout 15 mils thickness, prepared as above, was elongated 100% at 20inches per minute and immediately allowed to retract at a similar speed,the hysteresis loss (energy of elongation-energy of retraction100)/energy of elongation was found to be 30% or less and for the bestpressure sensitive adhesives to be in the range of 5 to 10%. In allinstances, the hysteresis test samples after testing retracted to within5% of their original length.

It has been discovered that acceptable pressure sensitive adhesiveswithin the scope of this invention can only be produced when at leastabout 75 parts of a tackifying resin or mixture of tackifying resins,having the particular characteristics hereinafter described, areemployed per 100 parts of the polymer formed by the in-situ coreactionof the organic polyisocyanate. with the diene telechelic polymer and,when utilized, the reactive polyester, polyether, extender andcrosslinking compound.

To provide the pressure sensitive adhesives of this invention having animproved balance of tack, peel adhesion and creep resistance, it isnecessary that virtually all of the tackifying resin or mixture oftackifying resin employed be soluble in the diene telechelic polymer orwhen reactive polyether or polyester are used in their admixture withthe diene telechelic polymer to give solutions that are essentiallyhaze-free after being conditioned 24 hours at 25C. In making thissolubility determination, the temperature of the diene telechelicpolymer or its admixture with the reactive polyether or polyester can beraised, e.g. to l60-200F,* to facilitate the solvation of the tackifyingresins after which the temperature is lowered to 25C for the 24-hourperiod of conditioning. Additionally, to provide the necessary pressuresensitive adhesive properties, the tackifying resin or mixture oftackifying resins used should have a ball and ring softening point ofbetween about 60C and 140C. Representative of resins of this descriptionwhich may be used are rosin, hydrogenated rosin, polymerized rosin,pentaerythritol ester of hydrogenated rosin, glycerol ester ofhydrogenated rosin, glycerol ester of polymerized rosin, phenol-modifiedpentaerythritol ester of rosin, maleic anhydride-modified rosin androsin derivatives, oil-soluble phenol-aldehyde resins, terpene phenolicresins, polymerized pinenes and polymerized C hydrocarbon resins. Whenit is desired to produce pressure sensitive adhesives having adhesion topolar surfaces, the invention pressure sensitive adhesives should beprincipally formulated with one or more tackifying resins havingsomewhat of a polar character such as rosin, the rosin derivativeresins, and the phenol-containing resins. Conversely, when adhesion tononpolar substrates is required, then the major portion of thetackifying resins should be one or more of the nonpolar types such asthe polymerized pinenes and the polymerized hydrocarbon resins.Generally, it is observed that both the nonpolar and the somewhat polarresins are compatible to the desired extent in the diene telechelichomopolymers and in the diene telechelic copolymers made with onlyslightly polar vinyl monomers such as the vinyl aryls and the acrylateesters. However, when it is desired to produce a pressure sensitiveadhesive from a diene telechelic copolymer made with any appreciablequantity, e.g. mole percent or more, of the more polar vinyl monomerssuch as acrylonitrile or methacrylamide, then it may be necessary that aconsiderable portion, e.g. 30 weight percent or more and in someinstances a major portion of the tackifying resins utilized, be providedwith more polar-type tackifying resins, as for example, those formed bythe condensation of formaldehyde with an aliphatic or cyclic ketone suchas methyl ethyl ketone, methyl isopropyl ketone, cyclobutanone andcyclohexanone. While the upper limit of tackifying resin cannot beprecisely delineated, in most pressure sensitive adhesive formulations,not more than about 130 parts per 100 parts of the in-situ formedpressure sensitive adhesive polymer will be utilized.

For many applications, it is advantageous to further incorporate in theinvention pressure sensitive adhesives from about 1 to 30 parts per 100parts of the insitu-formed elastomer of a plasticizer having a polarcharacter to increase its tack properties. Specifically, it has beenfound that primary or secondary plasticizers for plastic resins such aspolyvinyl chloride, polyvinyl acetate, and so forth will impartincreased tack to the invention pressure sensitive adhesives.Illustrative of plasticizers that may be used are dioctyl phthalate, n-

octyl n-decyl adipate, tricresyl phosphate, chlorinated j paraffin,chlorinated cyclic hydrocarbons, dioctyl seba- I cate, low-molecularweight polyesters, low-molecular weight, liquid polyvinyl ethyl etherand so forth.

Conversely, when it is desired to diminish the peel adhesion of theinvention pressure sensitive adhesives as for example in the productionof removable labels, nonpolar hydrocarbon oils such as the paraffinicand naphthenic mineral oils will be used in the range of about 30 to 60parts per 100 parts of the in-situ-formed elastomer.

Additionally, in the process of this invention, a catalyst may be usedto accelerate the in-situ formation of the pressure sensitive adhesiveon the substrate web or the formation of an intermediate prepol asdiscussed hereinafter. Usually about 0.1 to 1.0 parts, per 100 parts ofthe total elastomer precursor reactants, of a catalyst such as dibutyltin dilaurate, stannous octoate, dimethyl-aniline and so forth willprovide the desired increase in the coreaction of the polyisocyanatewith the telechelic diene polymer and, if used, the reactive polyetheror polyester, extender and crosslinking compound. While a singlecatalyst is most usual, mixed catalyst systems may be required incertain cases to achieve special properties.

Conversely, sometimes, it may be necessary to utilize a minor quantityof an acid inhibitor such as p-tolucne sulfonic acid, chloroacetic acid,oxalic acid and so forth to neutralize any basic impurities present inthe elastomer precursor reactants such as the reactive polyester andpolyether which are often synthesized wtih basic type catalysts.

To facilitate the admixing of the pressure sensitive adhesiveingredients and its subsequent application to the substrate web, theremay be used a minor quantity of an organic solvent capable of solvatingall the pressure sensitive adhesive ingredients. Especially useful aresuch polar-like solvents as toluene, xylene, elastomery ketone,methylethyl ketone and butyl acetate. In some cases, it is possible tosubstitute for the polar-like solvents used up to about 50 percent byweight of a nonpolar solvent such as heptane, hexane and naphthalene.Besides reducing viscosity, the solvent is of further benefit inincreasing the pot life of the admixed pressure sensitive adhesiveingredients, thus permitting more flexibility in factory processingoperations. Usually 5 to 10 percent by weight dilution of the admixedpressure sensitive adhesive ingredients will be sufficient to achievethese desired results. However, when a highmolecular-weight dieneealstomer, as hereinafter discussed, is also employed in the inventionpressure sensitive adhesives, then as much as 40% to 45% by weightsolvent may be required to provide proper viscosity.

An especially unique and valuable embodiment of this invention residesin the use of up to about parts, per parts of the in-situ-formedpressure sensitive adhesive elastomer of a diene elastomer, which iscompatible therewith, in the pressure sensitive adhesive composition toaccelerate the solidification of the pressure sensitive adhesive afterit has been applied to the substrate web. Particularly effective are thestyrenebutadiene or styrene-isoprene type block copolymers having thestyrene-type segments terminally located such as is disclosed in U.S.Pat. No. 3,239,478 or the diene segment terminally located as isdisclosed in British Pat. Specification No. 888,624.

Other diene elastomers that may be used are natural rubber, polyisopreneand random copolymers of styrene and butadiene having a mooney viscosityof about 35 to 90 (ML-4'-2l2F). When at least about 15 parts andpreferably from about 25 to 60 parts of such diene elastomers areutilized, it is possible to wind up the substrate web into a roll, afterthe pressure sensitive adhesive has been cast on the web and the solventessentially all removed, where the balance of the in-situ formation ofthe pressure sensitive adhesive elastomer can occur during storage onthe roll at ambient temperatures without the adhesive layer flowing togive uneven adhesive thickness and hoop-stress lines caused by the everpresent variation in wind-up torque. A further valuable contributionimparted by the presence of the diene elastomer in this embodiment ofthe invention pressure sensitive adhesive is that it markedly reducesthe sensitivity of the composition to impurities present in theingredients, such as water, which can adversely affect the activehydrogen group/isocyanate stoichiometry, thereby permitting the day-inand day-out factory production of pressure sensitive adhesive productshaving uniform and consistent properties. When diene elastomers areused, the quantity of tackifying resins should be increased. In the caseof the block-type diene elastomer, it is increased an amount such thatthe ratio of the tackifying resin to elastomer (i.e., the total of thediene elastomer and the in-situ formed elastomer) is approximately thesame as would be used in its absence to give the desired adhesiveproperties. When a diene elastomer homopolymer or random copolymer isused, sufficient additional tackifying resin is used so that the ratioof added resin to the diene elastomer is at least 0.6. It may bedesirable to similarly increase other materials used in the inventionpressure sensitive adhesive to compensate for the dilution effect of thediene elastomer.

In addition to the above described ingredients, other adjuventmaterials, commonly utilized in pressure sensitive adhesivecompositions, may be employed in essentially the same manner in thepressure sensitive adhesive of this invention, such as antidegradants,UV- stabilizers, optical whiteners, color pigments and dyes, adhesionpromoters, reinforcing pigments and filler pigments, to impart theirspecial properties as is well known to those skilled in the adhesivearts.

In the practice of the invention process, the ingredients of thepressure sensitive adhesive may be combined and admixed in any order andby any means that provides a final homogenous liquid admixture andfurther provides sufficient time to transport the liquid admixture fromthe admixing means to the casting means and its subsequent casting untothe substrate web before any appreciable thickening or solidificationoccurs. Bearing in mind these requirements, it is necessary in preparingthe pressure sensitive adhesive products of this invention to firstdissolve all solid ingredients that are soluble, such as tackifyingresin, diene elastomer, antidegradant, extender or crosslinking agent,and homogenously predisperse any solid ingredients such as colorpigment, reinforcing pigment or filler pigment into part or all of thediene telechelic polymer and/or the reactive polyether, polyester orsolvents if present. When a diene elastomer is employed, some or all ofthe solid insoluble ingredients may advantageously be predispersed in iton rubber mixing equipment such as a Banbury or rubber mill, prior tosolvating it. After the presolvation and predispersion of the solidingredients, any remaining liquid ingredients and the organicpolyisocyanate are added either incrementally or in one addition andhomogeneously dispersed. When a stoichiometric excess of organicpolyisocyanate is first added to and permitted to react with a part ofthe total diene telechelic polymer and/or reactive polyether orpolyester, if present, then an isocyanate prepol is formed whichminimizes isocyanate toxicity and facilitates handling, proportioningand subsequent admixing in factory processing operations and isconsequently a preferred mode of practicing the invention process.Alternatively, when these benefits are not required, then all of theingredients after presolvation and predispersion of the solidingredients may be admixed at one time employing the one-shot process toform the final pressure sensitive adhesive composition. As will be knownto those skilled in the art, when extremely reactive extenders orcrosslinking agents or hot catalysts are employed, they are desirablyadded last to ensure a satisfactory admixing of the other ingredients.

After all of the ingredients of the invention pressure sensitiveadhesive composition have been homogeneously admixed, the liquidadmixture is applied to a substrate web which could be paper, plasticfilm, metal foil, release paper and so forth, by any conventionalcasting means that is capable of metering and applying the desiredthickness uniformly across the web such as a wire-wound rod, a knifecoater, a reverse roll coater and so forth. If solvents are present, thecoated substrate web is then desirably heated to accelerate solventremoval and initiate the in-situ formation of the solid pressuresensitive adhesive by heating means such as a circulating hot air oven,infrared heaters or heated drums. The coated web is then wound-up on astorage roll where the in-situ formation of the invention pressuresensitive adhesive occurs within a few hours at elevated storagetemperature (e.g. 120 to 180F) or within 1 to 7 days at ambienttemperatures depending upon the reaction kinetics of the particularformulation being used. When solvent is not present, then heating priorto windup of the web is optional depending on the nature of thesubstrate web, the pressure sensitive adhesive formulation and thedesired end product. For webs and formulations subject to considerablehoop stress variations in the roll, which can cause visable adhesivelayer thickness variations, then the pressure sensitive adhesive layershould be partially set up or solidified by a prewind-up heating to anextent that will prevent any appreciable flow of the adhesive layer andthe consequent introduction of hoop stress lines in the product duringstorage on the roll.

When the invention pressure sensitive adhesive is first applied to arelease paper rather than directly to the end-product substrate web,such as a plastic film or metal foil, then the adhesive-coated releasepaper and the end-product substrate web are laminated together to form asandwich having the adhesive centrally located prior to being wound up.Normally, highest adhesion between the end-product substrate web andadhesive is obtained when they are laminated together prior tocompletion of the in-situ formation of the pressure sensitive adhesivelayer deposited on the release paper.

For pressure sensitive adhesive products having no release paper butrather relying on the release properties of the side of the end-productweb opposite the coating, the it may be desirable in some instances to,in essence, complete the in-situ formation of the invention pressuresensitive adhesive prior to wind-up in a storage roll to ensure that theadhesive layer preferentially adheres to the coated side of the web andreleases from the opposite side when the product is subsequently unwoundfor use. This, however, may not be necessary when the opposite side ofthe product web is pretreated with a release coating.

Because, at most, only a minor quantity of the total elastomer in thepressure sensitive adhesive compositions of this invention is providedby a solid elastomer, viz. a maximum of parts of the diene elastomer perparts of the in-situ formed elastomer, and further because of thelimited solvent employed, viz. about 45% or less solvent by weight ofthe liquid pressure sen- 17 sitive adhesive composition being cast, itis possible to dry the liquid pressure sensitive adhesive compositions,after casting on the substrate web when solvent is present, considerablyfaster than conventional pressure sensitive adhesives based entirely ona solid elastomer, free of voids and bubbles. As a consequence of thisproperty, the pressure sensitive adhesives of this invention may bedried with shorter length heating means. or conversely, if conventionalheating means are used, more rapidly.

EXAMPLES In Examples 1 to 10 tabulated in the following table toillustrate various embodiments of the pressure sensitive adhesives ofthis invention, all parts are by weight. The final pressure sensitiveadhesive compositions were prepared by homogeneously admixing Part A,consisting in the main of the diene telechelic polymer and thetackifying resin, with Part B, consisting essentially of thepolyisocyanate. In all of the examples, Part A was made by predissolvingthe tackifying resin in the diene telechelic polymer and then adding andhomogeneously dispersing the balance of the ingredients. In Examples 3and 10 the diene elastomer, Kraton 1107 employed was predissolved in theheptane and toluene solvents prior to being admixed with Part A. InExamples l to 4 to 10, Part A was allowed to age for a period of timeafter the monoisocyanate, Monduro had been added to the diene telechelicpolymer to allow essentially complete reaction therewith admixing withPart 3 B. In Examples 2, 3, and 10, the organic polyisocyanate of Part Bwas prereacted with part of the telechelic polymer to form anisocyanate-terminated prepolymer prior to the admixing of Parts A and B.

After the homogeneous admixing of Parts A and B, the final liquidpressure sensitive adhesive composition was cast onto a siliconeresin-treated release paper in sufficient quantity to give the finalin-situ formed thickness indicated and conditioned in a circulating hotair oven for minutes at 175F to remove the solvent and initiate thein-situ formation of the pressure sensitive adhesives. The pressuresensitive adhesive-coated side of the release paper, after cooling toroom tempera- 10 ture, was then laminated to a plastic substrate web,

which in Examples 1, 2 and 4 to 10 was a 2 mil film of biaxiallyoriented polyethylene terephthalate, and which in Example 3, was a 2 milfilm polypropylene used as received. and the resulting laminateconditioned for at least an additional 48 hours at ambient temperature(22 to 25C) to complete the in-situ formation of the pressure sensitiveadhesive prior to removing the release paper and testing the pressuresensitive adhesivecoated plastic web.

The tack, peel adhesion and creep resistance values for each examplewere obtained from test specimens that were prepared and tested asspecified in test methods PSTC-6 for tack, ASTM D-903-49 for peeladhesion, and PSTC-7 for creep resistance. In the peel adhesion andcreep tests, No. 304 stainless steel test panels were used and thelaminated test specimens were conditioned 48 hours at 25C prior totesting. Peel adhesion was determined with an Instron Model 1 130 testerand the reported values represent the average force required forseparation. Creep resistance was determined with a 2 lb. load and in a90 i 0.5F environment. Prior to testing, the creep test specimens werepreconditioned for 24 hours at the 90 i0.5 test temperature.

TABLE OF EXAMPLES PART A 1 2 3 4 5 6 7 8 9 10 Poly BD R-M (l) 58.8 58.870 7O Kraton 1107 (2) 60 Poly- BD CN-lS (3) 70 Hycar CTBN (4) 70 HycarMTBN (s) 70 Poly BD CS15 (6) 70 Poly BD R-45HT (7) 38 Super Beckacitc2000(8) 80 80 80 8O 80 80 40 Fora] (9) 32 40 40 40 40 40 22 104Piccolyte Alpha 1 15(10) 100 35 Piccolytc Alpha 85 (1 l) Ccllolyn 21(l2) l0 Mondur O (13) 0.9 1.9 0.5 0.5 0.5 0.5 0.9 2.7 Thanol SF 1500(14)20 20 20 20 20 20 20 20 Water 2.5

EDBC (l6 8 l0 10 10 Kodaflex AD-2( 17) 15 15 15 6.4 15 Santicizcr 160l8) l5 Toluene 162 50 14 50 Heptane 52 Methyl ethyl Ketone l0 DibutylTin dilaurate 0.5 0.5 1.0 O 5 0 5 O 5 0.5 0 5 0 5 0 5 Ethyl 330 (20) 2Uvinul N-539 (21) 4 lsonol C-lOO 15) 2.8 0.5 0.5 5.6 0.5

Part B 1 2 3 4 5 6 7 8 9 1O Arochlor 1254 (22) 30 10 Santicizer 160 5 l515 15 l5 l2 Hylene W (23) 9.56 9.56

Isonate 390 P(24) 16.2 25.8 12.4 12.4 12.4 12.4 13.65 12 Piccolyte Alpha1 l5 (10) 52 Foral 105 (9) 18 22 4 Poly BD R-45 M( l) 31.20 31.20

Toluene 10 24 56 Poly an R-45HT 7) i 32 Tack (inches) 8 4.2 1.5 15 2 1515 8 6 (rut-p Resistance (hrs) 95 171 300 300 5 Gauge (Mils) 1.5 1.5 1.51.5 4 5 4.5 5 1.5 1.5 Peel Adhesion (PLi) 9 w 3.5 3.2 6.5 12.5 2 1.5 8.51.5 6.8

Poly B-D R-45M hydroxyl-terminated polybutadiene having equivalentweight of 1250 and an average of 2.] to 2.3 7 hydroxyl groups permolecule.

Kraton l l07 styrene-isoprcne-styrcne block copolymer having aBrookfield viscosity of 3000 cps at a 25% total solids in toluene.

Poly B-D CN-l hydroxyl-terminated 85/15 butadiene acrylonitrilccopolymer having an equivalent weight of 1667 and approximately twohydroxyl groups per molecule. Hycar CTBN carboxyl-terminatedbutadiene-acrylonitrile copolymer having l9.4'71 bound acrylonitrile, anaverage molecular weight of 3270 and a functionality of 1.74.

Hycar MTBN thiol-terminatcd butadiene acrylonitrile copolymer having 24%bound acrylontrilc, an average molecular weight of 1700 and afunctionality of 1.6.

Poly B-D CS-l5 hydroxyl-terminated 75/25 butadiene-styrene copolymerhaving an equivalent weight of 1538 and approximately two hydroxylgroups per molecule. Poly Bd R-45HT hydroxyl-terminated polybutadienehaving an equivalent weight of 1358 and an average of about two hydroxylgroups per molecule.

Super Beckacitc 2000 polytcrpcne phenolic resin having a softening pointof about 105C.

Foral I05 pentacrythritol ester of saturated abietic acid having asoftening point of about 105C.

Piccolyte Alpha ll5 alpha pinene resin having a softening point of aboutll5C.

Piccolyte Alpha 85 alpha pinene resin having a softening point of about85C.

Cellolyn 21 hydroabietyl phthalate having a softening point of about63C.

Monduro octdeeyl isocyanate Thanol SF- 1 500 propylene oxide adduct ofglycerine having an equivalent weight of about 490.

lsonol C-lOO- N.N-bis {2-hydroxyl propyl] aniline EBDC liquid polyvinylether (tacky plasticizer) Kodaflcx AD-2 high molecular weight polymericplasticizer having an acid number of l3, a refractive index, n25C/D of1.4824, and a specific gravity 20 /20 C of L041.

Santicizcr I60 butyl benzyl phthalate.

Shelfcx 37lN parafinic mineral oil.

Ethyl 330 l,3,5-trimethyl-2,4,6-tris 3,5-di-tcrt-butyl-4-hydroxybcnzyl)benzene.

Uvinul N-539 Octyl 2,2-diphenyl-l-cyanoacrylate. Arochlor 1254chlorinated biphenyl having 54% chlorine. Hylene W 4.4'- methylene bis(cyclohexylisocyante). lsonate 390 P mixture of p,p' methylene diphenyldiisocyanate and polymethylene polyphenyl isocyanate having NCO contentof about 32% Example 1 illustrates that a general purpose pressuresensitive adhesive of this invention having excellent peel adhesion canbe made with a blend ofa hydroxylterminated polybutadiene and a reactivepolypropylene ether triol. Noteworthy is the use in Example 1 of partsof Kodaflex AD-2 and 5 parts of Santicizer 160 for a total ofapproximately parts of vinyl resin-type plasticizers per 100 parts ofthe in-situ formed elastomer component of the pressure sensitiveadhesive to enhance tack, an expedient that is not possible withconventional pressure sensitive adhesives made with hydrocarbonpolymers.

This pressure sensitive adhesive composition, when utilized on aplasticized polyvinyl chloride web or adherent surface, has demonstratedexcellent resistance to plasticizer migration, showing less than a 20%decrease in peel adhesion on accelerated heat aging. By way ofcomparison, conventional pressure sensitive adhesives based on ahydrocarbon polymer will generally lose at least 50% of its originalpeel adhesion and, as a consequence, normally would not be suitable forsuch applications.

Example 2 illustrated the preparation of a pressure sensitive adhesivehaving an excellent balance of physical properties employing theprepol-mixing technique and sans any solvent. Because it is made with analiphatic diisocyanate it exhibits better resistance to sunlightexposure than do the general purpose pressure sensitive adhesives of theprior art that are based on the hydrocarbon polymers.

As previously described, the adhesive composition of Example 3 wasapplied to a polypropylene web used as received and having no specialprimer to obtain adhesion to the adhesive layer. Even so, it exhibitedexcellent tack and creep resistance and adequate peel adhesion withfailure occuring principally to the metal rather than to thepolypropylene web. It was observed that the pressure sensitive adhesiveof Example 3 exhibits excellent tack at low temperatures, for example40F or lower, as compared to conventional polyacyrilic ester-basedpressure sensitive adhesives. Further, the composition of Example 3possesses excellent resistance to battery acid. The polypropylene webcoated with the pressure sensitive adhesive composition of Example 3when adhered to a rigid PVC substrate and preconditioned for 72 hours at25C and 10 minutes at F, exhibited onlyone-thirtysecond to onesixteenthinches of edge separation (undercutting) after being in contact withbattery acid (H SO for 7 days at 175F, indicating its eminentsuitability for battery labels. The best commercially available pressuresensitive adhesive products recommended for battery labels (based oncrosslinked acrylic ester copolymers) when similarly tested, had morethan twice this amount of edge undercutting, viz. four-sixteenths tofivesixteenths inches. Because of their ability to adhere to non-polarsurfaces and their resistance to acid environments, invention pressuresensitive adhesive compositions of the type exemplified in Example 3, inwhich non-polar resins provide a major portion of the tackifying resins,constitutes one of the preferred commercial embodiments of thisinvention.

Example 3 also illustrates that these advantages can be obtained evenwhen a considerable portion, viz. 43% of the pressure sensitive adhesiveelastomer com ponent is supplied by a diene elastomer. In thisconnection, it was observed that when a diene elastomer is employed, inthe practice of this invention, more consistent pressure sensitiveadhesive properties are obtained when it is predissolved in the dienetelechelic polymer and/or solvents, if used, rather than in the organicpolyisocyanate.

Example 4 illustrates that water can be used, if desired, in theformulation of the pressure sensitive adhesives of this invention whenspecial properties are required. The pressure sensitive adhesive ofExample 4 because of its low tack permits the production of pressuresensitive products that can be slidably positioned on an adhered surfaceand yet give a high order of ultimate peel adhesion and creepresistance. While more than one equivalent weight of water perequivalent weight of the diene telechelic polymer and reactive polyetherwas present in Example 4, only about one equivalent weight was reactedbecause of the limited quantity of polyisocyanate, viz. 2 equivalents,employed which, because of the catalyst used, preferentially reactedfirst with the hydroxyl groups present.

Example 5 and 8 demonstrate that satisfactory pressure sensitiveadhesives can be made from hydroxylterminated, random diene copolymers,when desired, in place of the diene homopolymers', Example 5 being madewith a dihydroxylterminated copolymer of butadiene containingapproximately 15% of randomly copolymerized acrylonitrile, while Example8 was derived from a dihydroxy-terminated butadiene copolymer containingabout 25% of randomly copolymerized styrene.

Examples 6 and 7 further demonstrate the use of random copolymers in thepressure sensitive adhesives of this invention and, in addition,illustrate the suitability of carboxyl groups and mercaptan (thiol)groups for coreaction with the polyisocyanate in the in-situ formationof the pressure sensitive adhesive after being cast on the substrateweb.

Example 9 illustrates the versatility and formulating latitude possessedby the pressure sensitive adhesives of this invention. Because of thisthe adhesive technologist can formulate the pressure sensitive adhesiveof this invention to provide a wide spectrum of properties to meet thespecification requirements of a number of different end-useapplications. In particular, the pressure sensitive adhesive of Example9 was formulated with a considerable quantity of a paraffin mineral oilto provide an adhesive having reduced tack and peel adhesion withreasonable retention of creep resistance, a balance of propertiesespecially desirable for removal pressure sensitive adhesive products.In contradistinction, conventional hydrocarbon pressure sensitiveadhesives when so formulated exhibit less than one hour of creepresistance.

Example 10 illustrates a second formulation employing a diene elastome'rin the pressure sensitive adhesives of this invention and particularly,the increased factory processing speeds that can be achieved with itsuse. With the composition of Example 10, it is possible to apply anadhesive layer at a coating weight of 2 gms/lOO in. of substrate atspeeds of up to 150 feet per minute employing as the solvent-evaporationmeans, high intensity infrared heaters having a length of only 6 feet,and a further run of 9 feet for cooling prior to wind-up. Conventionalpressure sensitive adhesives based on solid elastomers, on the otherhand, typically cannot be run at this coating weight at a speed much inexcess of about 90 feet per minute when dried in the circulating hot airovens of 100 to 150 feet length commonly used in the pressure sensitiveadhesive industry. Because of this reduced length of the heating meansre' quired by the invention process when solvents are employed,substrate web scrap losses are reduced, typically to 3% or less ascompared to the 7 to 10% that are common in todays pressure sensitiveadhesive production. Further, it is manifest that the reduced length ofthe heating means and/or increased speed that are typical in theproduction of the invention pressure sensitive adhesives significantlyreduces the capital investment required to practice the invention andhence lower fixed costs assessed to amortization.

The pressure sensitive adhesive composition of the present inventionachieves its final properties of a viscoelastic pressure sensitiveadhesive mass by the controlled chain extension, branching, andcross-linking of certain liquid, active hydrogen terminated elastomersby di-isocyanates or poly-isocyanates in the presence of a highconcentration of tackifying resins. By controlling chain extension,cross-linking, branching, resin composition, resin concentration, otheradditives, and other factors, the formulator has at his disposal,sufficient sophisticated controls to enable him to tailor this system,to many diversified applications that require special properties withrespect to specific adhesion, peel, creep, tack, and other functionalcharacteristics.

From the foregoing description and examples, it can be seen that theinvention provides the adhesive technologist with a unique new class ofpressure sensitive adhesives that is capable of providing a spectrum ofproperties previously unattainable with the compositions known to theprior art. Particularly unique and valuable is the capability of theinvention to provide pressure sensitive adhesives having a desirablebalance of properties for a wide variety of applications running thegamut from removal to permanent pressure sensitive adhesive productsthat, depending on its formulation, adhere to either polar or non-polarsurfaces, having low to high tack and low to high peel adhesion all withsuperior creep resistance, and exhibiting these properties over a widetemperature range and under a variety of potentially degradingenvironmental conditions.

Further, it has been demonstrated that the pressure sensitive adhesivesof this invention permit the use of production processes that minimizeand in some cases obviate the problems and disadvantages of the solventprocess most widely used by the pressure sensitive adhesive industry.Even when solvent is used in the process of this invention, it has beenshown that half or less of the quantity customarily employed by thesolvent pressure sensitive adhesive process will normally be required.Additionally, it has been shown that, because more than half of thefilm-former in the invention pressure sensitive adhesive arelow-molecular-weight materials at the time of solvent removal, solventevaporation rates can be many times faster thus minimizing the lengthand cost of solvent removable means and at the same time, because of thereduced length of the solvent removing means, dramatically reducing theproduction of off-spec products.

All of these advantages and objectives have been achieved with materialsthat have been known and available to the art for a number of yearsprior to applicants invention. In particular, typical diene telechelicpolymers employed in Applicants invention and suggested uses includingadhesives are generally shown in US. Pat. No. 3,427,366, assigned toSinclair Research, as well as Product Data Bulletin No. 505, revisedJune 1967 published by Sinclair Petrochemicals Inc. Further illustratingisocyanate-reactive polymers and products made therefrom are theteachings contained in US. Pat. Nos. 3,190,848; 3,245,954; 3,381,861 and3,392,154 and British Pat. Specification No. 574,901. A class of dieneelastomers and tackifying resins for pressure sensitive adhesives isshown in US. Pat. No. 3,239,478.

While a full and complete description of the invention has beenpresented, other modifications based on these teachings within thespirit and scope of the following claims will be apparent to thoseskilled in the art and are meant to be covered thereby.

What is claimed is: i

l. A process for making a urethane base pressure sensitive adhesivecomposition which comprises reacting an isocyanate-reactive componenthaving isocyanate-reactive functionality and which includes a liquiddiene telechelic polymer material having an average of at least aboutl.6 essentially terminal, isocyanate-reactive functional groups perpolymer molecule,

each of said essentially terminal functional groups being attached toone of the last three carbon atoms at an end of the polymer moleculewith a coreactive component having isocyanate functionality and whichincludes I an organic polyisocyanate material capable of coreacting withsaid isocyanate-reactive functional groups of said diene telechelicpolymer material,

said polyisocyanate material having an average number of isocyanatefunctional groups greater than one,

said isocyanate functional groups being reactive with theisocyanate-reactive functional groups of the diene telechelic polymermaterial to increase the average molecular weight and modify themolecular structure of the diene telechelic polymer material,

the ratio of isocyanate functional groups to isocyanatereactivefunctional groups being in the range from about .75 to l to about 1.2 tol,

in the presence of a tackifying resin material,

to form an elastomer base material in the presence of said tackifyingresin material,

said tackifying resin material being present in the amount of at leastabout 75 parts by weight of tackifying resin material per lOO parts byweight of said elastomer base material,

said tackifying resin material being sufficiently compatible with saidelastomer base material that said tackifying resin material is solublein said reactive component at 25C,

so that said tackifying resin renders said elastomer base materialtacky, and

wherein the step of reacting said isocyanate-reactive component withsaid coreactive component in the presence of said tackifying resinmaterial comprises,

mixing said isocyanate-reactive component with said coreactive componentin the presence of said tackifying resin material to form a mixture,

applying said mixture to a substrate, and curing said mixture in situ onsaid substrate.

2. A process in accordance with claim 1, wherein said mixture includes aplasticizer material.

3. A process in accordance with claim 1, wherein said mixture includes ahigh molecular weight; polymeric, solidification agent which is a solidelastomeric polymer which is capable of reversible elongation, and

said solidification agent being present in an amount up to about 90parts by weight per 100 parts by weight of said elastomer base material.

4. A process in accordance with claim 1, wherein said mixture prior toapplication to said substrate includes a solvent.

5. A process in accordance with claim 4, wherein said solvent is removedprior to completion of curing in situ.

6. A process in accordance with claim 1, wherein said mixture includes acatalyst for catalyzing the in situ curing of said mixture.

7. A process in accordance with claim 1, wherein the ingredients of saidisocyanate-reactive component are pre-mixed together to form anisocyanatereactive component mixture, then said isocyanate-reactivecomponent mixture is mixed with said coreactive component in thepresence of said tackifying resin material.

8. A process in accordance with claim 7, wherein the tackifying resinmaterial and the ingredients of said isocyanate-reactive component arepre-mixed together to form said isocyanate-reactive component mixture.

9. A process in accordance with claim 1, wherein said substrate isstored subsequent to completion of curing in situ.

10. A process in accordance with claim 1, wherein the step of curingsaid mixture in situ comprises heating said mixture on said substrate,then storing said substrate. 11. A process in accordance with claim 10,wherein said storing occurs at an elevated temperature. 12. A process inaccordance with claim 10, wherein said storing occurs at ambienttemperature. 13. A process in accordance with claim 1, wherein saidmixture prior to application to said substrate includes a solution of ahigh molecular weight, polymeric solidification agent in a solvent, saidsolidification agent being a solid elastomeric polymer which is capableof reversible elongation. 14. A process in accordance with claim 1,wherein said substrate comprises a release paper, and subsequent toapplication of said mixture to said release paper, said paper islaminated to an endproduct substrate web with said mixture disposedbetween said release paper and said web. 15. A process in accordancewith claim 14, wherein said release paper is laminated to said web priorto completion of said curing in situ. 16. A process in accordance withclaim 1, wherein a major portion of said curing occurs in situ on saidsubstrate.

1. A process for making a urethane base pressure sensitive adhesivecomposition which comprises reacting an isocyanate-reactive componenthaving isocyanate-reactive functionality and which includes a liquiddiene telechelic polymer material having an average of at least about1.6 essentially terminal, isocyanate-reactive functional groups perpolymer molecule, each of said essentially terminal functional groupsbeing attached to one of the last three carbon atoms at an end of thepolymer molecule with a coreactive component having isocyanatefunctionality and which includes an organic polyisocyanate materialcapable of coreacting with said isocyanate-rEactive functional groups ofsaid diene telechelic polymer material, said polyisocyanate materialhaving an average number of isocyanate functional groups greater thanone, said isocyanate functional groups being reactive with theisocyanate-reactive functional groups of the diene telechelic polymermaterial to increase the average molecular weight and modify themolecular structure of the diene telechelic polymer material, the ratioof isocyanate functional groups to isocyanatereactive functional groupsbeing in the range from about .75 to 1 to about 1.2 to 1, in thepresence of a tackifying resin material, to form an elastomer basematerial in the presence of said tackifying resin material, saidtackifying resin material being present in the amount of at least about75 parts by weight of tackifying resin material per 100 parts by weightof said elastomer base material, said tackifying resin material beingsufficiently compatible with said elastomer base material that saidtackifying resin material is soluble in said reactive component at 25*C,so that said tackifying resin renders said elastomer base materialtacky, and wherein the step of reacting said isocyanate-reactivecomponent with said coreactive component in the presence of saidtackifying resin material comprises, mixing said isocyanate-reactivecomponent with said coreactive component in the presence of saidtackifying resin material to form a mixture, applying said mixture to asubstrate, and curing said mixture in situ on said substrate.
 1. APROCESS FOR MAKING A URETHANE BASE PRESSURE SENSITIVE ADHESIVECOMPOSITION WHICH COMPRISES REACTING AN ISOCYANATE-REACTIVE COMPONENTHAVING ISOCYANATEREACTIVE FUNCTIONALITY AND WHICH INCLUDES A LIQUIDDIENE TELECHELIC POLYMER MATERIAL HAVING AN AVERAGE OF AT LEAST ABOUT1.6 ESSENTIALLY TERMINAL, ISOCYANATEREACTIVE FUNCTIONAL GROUPS PERPOLYMER MOLECULE, EACH OF SAID ESSENTIALLY TERMINAL FUNCTIONAL GROUPSBEING ATACHED TO ONE OF THE LAST THREE CARBON ATOMS AT AN END OF THEPOLYMER MOLECULE WITH A COREACTIVE COMPONENT HAVING ISOCYANATEFUNCTIONALITY AND WHICH INCLUDES AN ORGANIC POLYISOCYANATE MATERIALCAPABLE OF COREACTING WITH SAID ISOCYANATE-REACTIVE FUNCTIONAL GROUPS OFSAID DIENE TELECHILIC POLYMER MATERIAL, SAID POLYISOCYANATE MATERIALHAVING AN AVERAGE NUMBER OF ISOCYANATE FUNCTIONAL GROUPS BEING REACTIVEWITH THE SAID ISOCYANATE FUNCTIONAL GROUPS BEING REACTIVE WITH THEISOCYANATE-REACTIVE FUNCTIONAL GROUPS OF THE DIENE TELECHELIC POLYMERMATERIAL TO INCREASE THE ABERAGE MOLECULAR WEIGHT AND MODIFY THEMOLECULAR STRUCTURE OF THE DIENE TELECHELIC POLYMER MATERIAL, THE RATIOOF ISOCYANATE FUNCTIONAL GROUPS TO ISOCYANATEREACTIVE FUNCTIONAL GROUPSBEING IN THE RANGE FROM ABOUT .75 TO 1 TO ABOUT 1.2 TO 1, IN THEPRESENCE OF A TACKIFYING RESIN MATERIAL, TO FORM AN ELASTOMER BASEMATERIAL IN THE PRESENCE OF SAID TACKIFYING RESIN MATERIAL, SAIDTACKIFYING RESIN MATERIAL BEING PRESENT IN THE AMOUNT OF AT LEAST ABOUT75 PARTS BY WEIGHT OF TACKIFYING RESIN MATERIAL PER 100 PARTS BY WEIGHTOF SAID ELASTOMER BASE MATERIAL, SAID TACKIFYING RESIN MATERIAL BEINGSUFFICIENTLY COMPATIBLE WITH SAID ELASTOMER BASE MATERIAL THAT SAIDTACKIFYING RESIN MATERIAL IS SOLUBLE IN SAID REACTIVE COMPONENT AT 25*C,SO THAT SAID TACKIFYING RESIN RENDERS SAID ELASTOMER BASE MATERIAL TACKYAND WHEREIN THE STEP OF REACTING SAID ISOCYANATE-REACTIVE COMPONENT WITHSAID COREACTIVE COMPONENT IN THE PRESENCE OF SAID TACKIFYING RESINMATERIAL COMPRISES, MIXING SAID ISOCYANATE-REACTIVE COMPONENT WITH SAIDCOREACTIVE COMPONENT IN THE PRESENCE OF SAID TACKIFYING RESIN MATERIALTO FORM A MIXTURE, APPLYING SAID MIXTURE TO A SUBSTRATE, AND CURING SAIDMIXTURE IN SITU ON SAID SUBSTRATE.
 2. A process in accordance with claim1, wherein said mixture includes a plasticizer material.
 3. A process inaccordance with claim 1, wherein said mixture includes a high molecularweight; polymeric, solidification agent which is a solid elastomericpolymer which is capable of reversible elongation, and saidsolidification agent being present in an amount up to about 90 parts byweight per 100 parts by weight of said elastomer base material.
 4. Aprocess in accordance with claim 1, wherein said mixture prior toapplication to said substrate includes a solvent.
 5. A process inaccordance with claim 4, wherein said solvent is removed prior tocompletion of curing in situ.
 6. A process in accordance with claim 1,wherein said mixture includes a catalyst for catalyzing the in situcuring of said mixture.
 7. A process in accordance with claim 1, whereinthe ingredients of said isocyanate-reactive component are pre-mixedtogether to form an isocyanate-reactive component mixture, then saidisocyanate-reactive component mixture is mixed with said coreactivecomponent in the presence of said tackifying resin material.
 8. Aprocess in accordance with claim 7, wherein the tackifying resinmaterial and the ingredients of said isocyanate-reactive component arepre-mixed together to form said isocyanate-reactive component mixture.9. A process in accordance with claim 1, wherein said substrate isstored subsequent to completion of curing in situ.
 10. A process inaccordance with claim 1, wherein the step of curing said mixture in situcomprises heating said mixture on said substrate, then storing saidsubstrate.
 11. A process in accordance with claim 10, wherein saidstoring occurs at an elevated temperature.
 12. A process in accordancewith claim 10, wherein said storing occurs at ambient temperature.
 13. Aprocess in accordance with claim 1, wherein said mixture prior toapplication to said substrate includes a solution of a high molecularweight, polymeric solidification agent in a solvent, said solidificationagent being a solid elastomeric polymer which is capable of reversibleelongation.
 14. A process in accordance with claim 1, wherein saidsubstrate comprises a release paper, and subsequent to application ofsaid mixture to said reLease paper, said paper is laminated to anend-product substrate web with said mixture disposed between saidrelease paper and said web.
 15. A process in accordance with claim 14,wherein said release paper is laminated to said web prior to completionof said curing in situ.